This program's objectives are to design, fabricate and test a low cost three dimensional micro-electrode array which has two hundred individually accessible electrodes. We have applied materials using laminar flex circuit technology in order to construct a readily adaptable array which will readily conform to concave or convex cortical surfaces, will detect a wide range of neural signals ranging from low to hi frequencies, will be effective for both stimulation and recording of neural tissue, will he biocompatible and will be easily configured by the researcher to either large or small numbered electrode arrays using the same physical device. Long term objectives of the program are to enable the production of array components which can be easily and inexpensively purchased and then put together to form custom arrays which can be used in cortical surface recordings. The first phase of the program is the testing of prototypes with measurement of biocompatibility, electrical and structural characteristics. The second phase of the program will involve animal studies recordings over a wide range of neural signals from evoked potentials to single unit recordings. We will also examine the feasibility of human use in the neurosurgical suite for use in procedures involving resection or ablation of damaged tissue. Other potential uses such as brain slice applications or use in tissue culture experimentation will also be explored. The array will prove useful to medical and research areas which utilize techniques in surface recording or stimulation of cerebral cortex. The array will be significantly less expensive than current 3-D configurations and will require only simple manipulations to change the geometry.